Commit 7ec9a684 authored by George Kadianakis's avatar George Kadianakis
Browse files

Service intro circuits are now 4-hop to avoid linkability by intro 

Now the circuits look like this:

	 client rend:   C -> G -> L2 -> Rend
	 client intro:  C -> G -> L2 -> M -> Intro
	 client hsdir:  C -> G -> L2 -> M -> HSDir
	 service rend:  C -> G -> L2 -> M -> Rend
	 service intro: C -> G -> L2 -> M -> Intro
	 service hsdir: C -> G -> L2 -> M -> HSDir
parent 9b464cdc

src/core/or/circuitbuild.c

+6 −5
Original line number Original line Diff line number Diff line
@@ -1394,16 +1394,14 @@ route_len_for_purpose(uint8_t purpose, extend_info_t *exit_ei) 
    return routelen;

    return routelen;





  switch (purpose) {

  switch (purpose) {

    /* These two purposes connect to a router that we chose, so

    /* These purposes connect to a router that we chose, so DEFAULT_ROUTE_LEN

     * DEFAULT_ROUTE_LEN is safe. */

     * is safe: */

  case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:

    /* hidden service connecting to introduction point */

  case CIRCUIT_PURPOSE_TESTING:

  case CIRCUIT_PURPOSE_TESTING:

    /* router reachability testing */

    /* router reachability testing */

    known_purpose = 1;

    known_purpose = 1;

    break;

    break;





    /* These three purposes connect to a router that someone else

    /* These purposes connect to a router that someone else

     * might have chosen, so add an extra hop to protect anonymity. */

     * might have chosen, so add an extra hop to protect anonymity. */

  case CIRCUIT_PURPOSE_C_GENERAL:

  case CIRCUIT_PURPOSE_C_GENERAL:

  case CIRCUIT_PURPOSE_C_HSDIR_GET:

  case CIRCUIT_PURPOSE_C_HSDIR_GET:
@@ -1413,6 +1411,9 @@ route_len_for_purpose(uint8_t purpose, extend_info_t *exit_ei) 
    /* client connecting to introduction point */

    /* client connecting to introduction point */

  case CIRCUIT_PURPOSE_S_CONNECT_REND:

  case CIRCUIT_PURPOSE_S_CONNECT_REND:

    /* hidden service connecting to rendezvous point */

    /* hidden service connecting to rendezvous point */

  case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:

    /* hidden service connecting to intro point. In this case we want an extra

       hop to avoid linkability attacks by the introduction point. */

    known_purpose = 1;

    known_purpose = 1;

    routelen++;

    routelen++;

    break;

    break;

src/test/test_circuitbuild.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -113,7 +113,7 @@ test_new_route_len_safe_exit(void *arg) 
  /* hidden service connecting to introduction point */

  /* hidden service connecting to introduction point */

  r = new_route_len(CIRCUIT_PURPOSE_S_ESTABLISH_INTRO, &dummy_ei,

  r = new_route_len(CIRCUIT_PURPOSE_S_ESTABLISH_INTRO, &dummy_ei,

                    &dummy_nodes);

                    &dummy_nodes);

  tt_int_op(DEFAULT_ROUTE_LEN, OP_EQ, r);

  tt_int_op(DEFAULT_ROUTE_LEN+1, OP_EQ, r);





  /* router testing its own reachability */

  /* router testing its own reachability */

  r = new_route_len(CIRCUIT_PURPOSE_TESTING, &dummy_ei, &dummy_nodes);

  r = new_route_len(CIRCUIT_PURPOSE_TESTING, &dummy_ei, &dummy_nodes);